By choosing \(\Psi _k[\phi ]\)  we can specify the flow of inessential couplings \(\zeta \) , which by their definition are those for which [1]}
\( \zeta \frac{\partial }{\partial \zeta } \Gamma _k[\phi ] = \mathcal {T}[\Phi ] := \Phi [\phi ] \cdot \frac{\delta }{\delta \phi } \Gamma _k[\phi ] - {\rm Tr}\, \mathcal {G}_k[\phi ] \cdot \frac{\delta }{\delta \phi } \Phi [\phi ] \cdot \mathcal {R}_k \,,\) 
